Die Drift von Mysidacea und Decapoda und ihre Bedeu­tung für die Ausbreitung von Neozoen im Main-Donau-System [The drift of Mysidacea and Decapoda and its significance for the disper­sion of neozoans in the Main-Danube system]

Abstract. Drift samples in the hydropower reservoirs of Geisling, Straubing and Vienna, and in the Sf. Gheorghe mouth branch of river Danube contained the Pontocaspian Mysidacea Limnomysis benedeni, Hemimysis anomala and Paramysis intermedia, and a few individuals of the Decapoda Atyaephyra desmaresti and Orconectes limosus. Further records were made using hand operated nets in the river Main, the Main-Danube-Canal and the river Danube. L. benedeni was for the first time recorded in the river Main; and H. anomala for the first time in the upper Danube and in Austria. All five species appeared in nocturnal drift samples, and the more frequent species, L. benedeni and H. anomala, additionally in diurnal drift samples. Four of these five species are known as neozoans with ample distribution in continental waters of Europe. Appearance of these crustaceans in drift samples may be indicative of a possible predisposition for dispersion by navigation.